Patent literature 1: JP 2010-208579 A
A load drive apparatus detects a current flowing through an inductive load such a linear solenoid by a current detection means, and controls drive of the inductive load while feeding back the amount of current. A failure mode of the load drive apparatus includes a short circuit (also referred to as a power source short circuit) in an upstream side of the inductive load and a short circuit (also referred to as a ground short circuit) in a downstream side of the inductive load. In order to detect these types of short circuits, various methods have been considered.
An electronic control unit in Patent literature 1 detects a ground short circuit by detecting a decrease of a current flowing through a current detection means side. The electronic control unit has, as a resistive element, a diode that is placed in series with the current detection means on a downstream side of a load. According this configuration, it may be possible to prevent a load current that flows through the load from going through the current detection means, and a decrease of current due to ground short circuit may easily be detected.
The inventor of the present disclosure has found the following.
A resistance value of a diode, which is used as a resistance element, is changed based on an I-V characteristic of the diode itself. It may be difficult to adjust the resistance value to a desired resistance value. The resistance value of the diode may be influenced by a noise by manufacture variation and temperature dependence of the I-V characteristics. Thus, variation of the load current due to a short circuit may be buried in the noise, and it may be difficult to obtain sufficient detection accuracy.